Abstract
In this paper we investigate the spin-resolved thermoelectric properties of strongly correlated molecular junctions in the linear response regime. The magnetic molecule is modeled by a single orbital level to which the molecular core spin is attached by an exchange interaction. Using the numerical renormalization group method we analyze the behavior of the (spin) Seebeck effect, heat conductance and figure of merit for different model parameters of the molecule. We show that the thermopower strongly depends on the strength and type of the exchange interaction as well as the molecule’s magnetic anisotropy. When the molecule is coupled to ferromagnetic leads, the thermoelectric properties reveal an interplay between the spin-resolved tunneling processes and intrinsic magnetic properties of the molecule. Moreover, in the case of finite spin accumulation in the leads, the system exhibits the spin Seebeck effect. We demonstrate that a considerable spin Seebeck effect can develop when the molecule exhibits an easy-plane magnetic anisotropy, while the sign of the spin thermopower depends on the type and magnitude of the molecule’s exchange interaction.
Highlights
In this paper we investigate the spin-resolved thermoelectric properties of strongly correlated molecular junctions in the linear response regime
An interesting situation occurs when the junction comprises a molecule of large spin, since the spin Seebeck effect is conditioned by intrinsic parameters of the molecule, such as an exchange interaction, magnetic anisotropy or the magnitude of the molecule’s s pin[41,42]
The focus is on the linear response regime with respect to the applied potential and temperature gradients, which justifies the usage of the numerical renormalization group (NRG) method[50,51] for the calculations
Summary
In this paper we investigate the spin-resolved thermoelectric properties of strongly correlated molecular junctions in the linear response regime. We demonstrate that a considerable spin Seebeck effect can develop when the molecule exhibits an easy-plane magnetic anisotropy, while the sign of the spin thermopower depends on the type and magnitude of the molecule’s exchange interaction. The spin-dependent thermoelectric properties of large-spin molecular junctions have already been studied in the case of weak coupling to the contacts[43,44,45,46], whereas the system’s behavior in the strongly correlated case remains to a large extent unexplored. This comprises the goal of this paper, which is to further extend the understanding of thermoelectricity in strongly correlated magnetic molecular systems. We believe that our study, by providing a comprehensive analysis of (spin) thermopower in the case of large-spin molecules, adds a new insight into the interplay of heat, charge and spin in magnetic molecules, contributing to further development of molecular spin caloritronics
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